Radiation Therapy

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Radiation therapy is a type of local treatment that uses high doses of radiation to kill cancer cells in a specific area. Cancer cells multiply rapidly and are more susceptible to radiation than healthy cells.1,2

There are generally two types of radiation therapy that may be used in the treatment of breast cancer: external beam radiation and internal radiation (also called brachytherapy). In external beam radiation, the beams are directed to the treated area from a machine. With internal radiation, radioactive materials are placed inside the body at the treated area and left in place for a period of time.1

Radiation therapy may be used:

  • After breast-conserving surgery, such as lumpectomy
  • After mastectomy to reduce the risk of recurrence1
  • To treat breast cancer that has spread to the lymph nodes under the arm (axillary lymph nodes)2
  • To shrink tumors and improve the symptoms of metastatic breast cancer that has spread to other parts of the body, like the bones or brain2

External beam radiation therapy

External beam radiation therapy is the most common type of radiation used to treat breast cancer. Traditionally, external beam radiation therapy is given on weekdays for approximately 6-7 weeks. Newer types of external beam radiation can give larger doses over a shorter duration in certain patients and include1:

  • Hypofractionated radiation therapy, which provides larger radiation doses over a shorter period of time as compared to more traditional radiation schedules
  • Intraoperative radiation therapy, in which a single large radiation dose is given in the operating room before the incision is closed
  • 3D-conformal radiotherapy, in which radiation is often given twice a day for 5 days using special machines

Internal radiation therapy/brachytherapy

Internal radiation therapy, or brachytherapy, uses a device that contains radioactive seeds or pellets. This device is implanted into the breast tissue where cancer has been removed for a short period of time.1

Possible side effects of radiation therapy

External beam radiation therapy often causes fatigue, a feeling of exhaustion that is not improved with rest. Radiation therapy can also affect healthy tissue where the radiation is directed and may cause redness, blistering or peeling of the skin. Radiation may also cause long-term side effects, including lymphedema, changes to the breast tissue or skin, numbness in the arm or hand, and/or damage to the ribs which could lead to fracture.1

When internal radiation therapy is used, side effects may include redness or bruising at the treatment site, breast pain, infection, fluid collection, and/or damage to the ribs which could lead to fracture.1

Radiation therapy for metastatic breast cancer

Depending on where breast cancer metastasizes, these tumors can cause pain, numbness, weakness, or other symptoms as the tumors press on surrounding tissues and interfere with the normal functioning of the body in that area. Radiation therapy may be used to help shrink metastases from breast cancer and alleviate the symptoms of these tumors. Using radiation therapy in this way is considered palliative, not curative, as the radiation will not cure the metastatic breast cancer but can help relieve symptoms. When radiation therapy is used for metastatic breast cancer, a radiation beam may only be needed a few times to treat the specific area.3

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